Electrical control system



Oct. 16, 19456 J. R. ALBERS 2,386,921

ELECTRICAL CQNTROL SYSTEM Fiied ma 10, 1945 FIG. 5

FIG. 2

INVENTOR JOHN" R. ALBERS BY% QA;L A %m;

HIS ATTORNEY Patented Oct. 16, 1945 ELECTRICAL CONTROL SYSTEM John R. Albers, Sioux City, Iowa, asslgnor to Wincharger Corporation; a corporation of Minnesota Application May 10, 1943, Serial No. 486,314

6 Claims.

This invention relates to electrical control systems and more particularly to such systems and associated apparatus for charging batteries.

In battery charging systems incorporating a generator which is driven by a variable speed prime mover such as an internal combustion engine or wind driven equipment, it is desirable to take maximum energy from the prime mover even at generator voltages which correspond, to vo1t ages below the maximum battery voltage. In other words, it is desirable to connect the generator to the battery whenever the generator voltage exceeds the actual battery voltage. In wind driven equipment, especially where such equipment is to be used in areas where low wind velocity prevails periodically, it is necessary to' take full advantage of the changing wind conditions for efiecting maximum battery charging. If the generator is connectedto the battery only in response to a wind blowing fast enough so that the generator voltage exceeds a voltage approximately equal to maximum battery voltage, regardless of the actual battery voltage, the wind driven generator may be driven for quite a long period of time at a voltage somewhat less than the critical voltage needed to close the circuit between the battery and generator and at a gen= erator voltage greater than the actual battery voltage. Under these conditions the available wind energy is lost.

In its broader aspects, this invention has for an object to provide a new and improved system and apparatus for connecting a source of variable voltage to a load of variable back electromotive' force, whenever the voltage of the source exceeds the voltage of the load. This invention has particular applicability to a battery charging system. It is therefore an object of this invention to provide an improved relay for connecting a generator to a battery in a battery charging system. Another object of this invention is to provide an improved relay in a battery charging system in which actuation of the relay is dependent upon battery voltage.

Another object of thisinvention is to provide improved means for supplying current from a source to a load of varying back electromotive force.

Still another object of this invention is to provide an improved and more eflicient battery charging system incorporating a variable speed prime mover, for example, in wind charging systems where the prime mover may turn. at a low speed for a considerable period of the day.

Another object of this invention is to provide an improved relay in a battery charging system wherein the relay is made sensitive to battery voltage, generator voltage and reverse current.

A further object of this invention is to provide an improved cutout relay in a battery charging system.

Another object of this invention is to provide improved means for connectin a battery charging generator to a battery, not only including means responsive to battery voltage and reverse current, but also to the condition of the battery.

Anoher object of the present invention is to provide compensating means for a cutout relay whereby it closes at a voltage only slightly greater than actual battery voltage instead'of at a voltage determined by the mechanical characteristics of the relay itself.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which:

Figure 1 shows a preferred embodiment of my invention, and

Figure 2 shows another embodiment of my invention.

In Figure l, a generator ill is connected to a battery I I through a relay i2, embodying my invention. The generator it is driven by a prime mover which may be an internal combustion engine, wind driven equipment, or the like.

The relay l2 has a stationary frame l3 having securely mounted thereon a cylindrical magnetizable core M upon which is mounted a current winding l5 and a voltage Winding it. These windings are arranged to transmit magnetic flux through the magnetizable core M in the same direction when the generator I (i charges battery it and in opposite directions when the battery I l tends to discharge through the generator ill.

The armature electric contact carrying member 11 of relay i2 is pivotally mounted on the frame it on a pivot I8, and has secured thereon a magnetizable member 19 which is attracted to the core 14 when sufiicient magnetism is set up due to current flowing through coil I6. Contact 20 is carried by the pivoted member I! and is insulated therefrom by means of insulation 2i through which contact 20 is supported on member 11. The pivoted member I! tends to rotate clockwise by reason of magnetic forces between core l4 and mag'netizable member IS. A tension spring 22 mounted between the stationary frame l3 and the projecting end I'LA of pivoted member 11 tends to rotate thepivoted member I! counterclockwise. A projection 23 on frame l3 serves as a stop in limiting thecounter-clockwise movement of pivoted lever I! about its pivot l8.

Electrical contact 24, mounted in cooperating relationship with movable contact 20, is secure- 1y fastened to stationary frame I3. but insulated therefrom by interposed insulation 25.

The generator I is connected electrically to, the battery H through a series circuit-including current coil l5 and contacts 20 and 24 of relay ii.

The voltage coil [6 is connected directly in parallel with the output terminals of generator II]. This coil is is adapted to transmit flux through the magnetizable core M in the same direction as that transmitted'by coil l5 when coil I5 is .energized by battery charging current. In other words, the coils l5 and I6 are arranged to act differentially when coil I5 is energized by battery discharge current.

A voltage sensitive coil 25 is mounted on a stationary frame extension IBA of frame 53 and a movable magnetizable member 21 is connected to pivoted member extension MA by a link i713 and is disposed within the magnetic field of solenoid coil 28 so asto be drawn downward thereby. When the coil 26 is energized a force is applied to the pivoted member ll tending to rotate it counter-clockwise about its pivot it. y

Coil 26 is made sensitive to battery voltage by connecting it in parallel to the battery l I.

The. efiect of connecting the movable magnet member 21 to the pivoted member extension A is to supplement the action of tension spring 22. When coil 26 is energized both the spring 22 and link l'lB, together with magnetizable member 27, tend to rotate pivoted member l'l counter-clockwise. Thus the efiect of connecting coil 26 in parallel with battery I l is to cause the net force tending to rotate member ll counter-clockwise to be a function of battery voltage. When the battery voltage is high, the action of tension spring 22 is supplemented to a greater degree than when the battery voltage is low. The net effect of this arrangement is that the contacts 29 and 2d are caused to be closed for low generator voltages when the battery voltage is low, and are caused to be closed only for higher generator voltages when the battery voltage is high.

Therefore, by the provision of the extra voltage coil 26 and associated connections there is provided an eflicient battery charging system. With the system herein disclosed, if the battery voltage.

is low, energy is taken from the generator and stored in the battery even when the generator is driven at low speed.

This efiect is of great importance in connection with a wind driven generator-since, especially in areas of low average wind velocity, it is necessary to take advantage of all possible wind energy, even when the wind is of very low velocity.. After a charging operation during which generator voltage has been high, the wind dies down and the generator voltage becomes less and less. The current through winding it correspondingly diminishes, and finally, as battery discharge current tends to flow through coil 55, the fiux set up by coil I5 is in opposition to the flux set up by winding l5. Consequently, the contacts 20 and 24 separate under the influence of tension spring 22 and solenoid 26.

Tension spring 22 is adjusted to cause the conably made for the condition when 'the'voltage of battery l I is lowest since then the supplementary action of-solenoid 28 is a minimum.

Figure 2 illustrates a modification of my invention in which certain structural features are identical with those shown in'Figure '1, and accordlngly parts in Figure 2 identical to the parts shown in Figure ,1 are given the the same reference numerals as correspondlngparts in Figure 1. I The relay of Figurez is responsive to the difference between generator voltage and battery voltage by reason of a circuit having a voltage coil H6 and unilateral conductive element or rectifier ill which are connected in series with the oppositely poled batteryand generator. The voltage coil H6, connected in a series circuit between the oppositely poled battery II and generator H), has current flowing therethrough only when the generator voltage exceeds the voltage of battery H because rectifier H1 is poled to prevent flow oi current in the opposite direction. Current coil H5, connected in series between the generator and battery and in series with contacts 20 and 24 through conductors I20 and Hi, is mounted on the same magnet core M as is the voltage coil H8. Coils H5 and H6 are adapted to transmit magnetic flux in the same direction when the generator voltage exceeds the battery voltage and when battelruy5 charging current flows through current coil In other words, the polarities of coils H5 and I I6 are such that, when the voltage of generator ill becomes less than the voltage of battery ll the battery discharge current which tends to flow through coil I I5 sets up a magnetic flux in opposition to that produced in coil H6 when it has current therethrough. The unilateral conductive element or rectifier Ill allows current to flow through coil H6 only when the voltage of gener- As the generator voltage becomes less than the battery voltage, the flux set up by coils H5 and I I8 correspondingly becomes less until the switch opens under the influence of tension spring H2. The tension spring I22 is preferably so adjusted that it causes contacts 29 and 24 to separate before battery discharge current fiows through current coil l l5.

Also it is to be noted that when contacts 20 and 2% have just closed, the serially connected coil H6 and rectifier Ill are shunted by the current coil l l5, and the fiux due to coil i ii decays slowly to a value less than was necessary to close contacts at and 25 and the charging current which builds up quickly through coil H5 is the principal factor in maintaining the relay in its circuit closing position. The large inductance of coil H6 does not allow the flux in coil H5 to change rapidly when the voltage across coil H6 changes. Also, since the unidirectional device Ill has a high resistance for the flow of reverse currents in the coil H6, a decrease of generator voltage below battery voltage would require reverse current to fiow through rectifier H! to cause coil flux to prevents such reverse current.

As battery discharge current tends to flow in current coil N5, the voltage induced in coil H6 by such current change in coil H causes a current to flow through unidirectional device H1 in its conducting direction so as to tend to neutralize the magnetic flux set up in core H by discharge current in coil 5. That is, rectifier Ill prevents induced current flow in coil H6 upon sudden increase 01' current in charging direction in coil H5, but allows current flow in coil H6 upon decrease of charging current in coil H5 or 'reversal of current flow in coil 5 so that such decrease or reversal of charging current in coil 5 is opposed, andchange of flux in core II is slowed down. Spring I22 is made strong enough to lift armature 11 during this slowed reversal of flux upon decrease of generator voltage below battery voltage.

chattering in the relay 0! Figure 2 may be avoided by making the voltage difierential between generator !0 and battery ll necessary to close the relay of suitable high value consistent with the voltage drops which appear in the battery charging circuit when contacts and 24 close. It is, of course, realized that battery charging current through coil H5 produces a flux in such direction as to help in maintaining the contacts 28 and 2% closed when battery charging necessary and the voltage coil H6 is a low voltage winding. The arrangement shown in Figure 2 lends itself to a more compact structure than does the arrangement shown in Figure 1, but because of its simplicity and ease of adjustment the arrangement shown in Figure 1 is preferred.

My invention in its broader aspects comprises the method and apparatus for producing a diliferential characteristic or eiifect and using that characteristic or effect for connecting a source of variable voltage to a circuit having a variable source of back electromotive force. In the arrangement shown in Figure l, the differential characteristic or effect is produced by the joint action of generator voltage on the actuating coil is and of battery voltage on the solenoid 26. In the arrangement shown in Figure 2, the difierential characteristic or eiIect is produced by the particular manner in which actuating coil tilt is connected in a series circuit including the battery and generator of polarity opposite to the battery polarity.

While I have shown and described the particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention in its broader aspects, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

I claim:

1. In asystem for connecting a source of variable voltage to a circuit including a, source of variable back electromotive force, an electrical circuit connections between said source of variable back electromotive force and last mentioned electromagnetic means such that current flows therethrough regardless of the magnitude of said source of variable voltage and causes urging of said contacts apart.

2. In a battery charging system, a battery, 8. generator for charging the battery, means for connecting the generator to the battery, said means including a contact member, means responsive to battery voltage and independent of generator voltage for biasing said contact member to circuit opening position, means responsive to generator voltage for moving the contact to circuit closing position against the force of said biasing means, and permanent switchless circuit connections between said battery and said battery voltage responsive means such that current flows therethrough regardless of the magnitude of the voltage of said generator and causes biasing of said contact member to circuit opening position.

3. In a battery charging system, a battery, a generator for charging the battery, means for connecting the generator to the battery, means for biasing said contact member to circuit opening position, means responsive to generator voltage for moving said contact member against said biasing means to circuit closing position, means responsive to battery voltage and independent of generator voltage for altering the effect on said member of said biasing means, and permanent switchless circuit connections between said battery and cattery voltage responsive means such that current flows therethrough regardless of the magnitude of generator voltage and aids the effeet on said member of said biasing means.

l. In combination, a relay for controlling the charging of a battery and having contacts which are opened and closed according to the movement of the relay armature, a battery, a voltage source, means responsive to source voltage for moving said armature in the direction to close said contacts, electromagnetic means responsive to battery voltage and independent of source voltage for moving said armature in the direction to open said contacts, and permanent switchless circuit connections between said battery and battery voltage responsive means such that current flows therethrough regardless of the magnitude of said voltage and causes movement of said.

armature in the direction to open said contacts.

5. In combination, a relay for controlling the charging of a battery and having contacts which are opened and closed according to the movement or the relay armature, a battery, a voltage source, means responsive to source voltage for moving said armature in the direction to close said contacts, means responsive to battery voltage and independent of source voltage for moving said armature in the direction to open said contacts, a spring normally biasing said contacts in open position, and a permanent switchless circuit connection between said battery and battery voltage responsive means such that current flows there- ,through regardless of the magnitude of said source voltage and causes movement of said armature in the direction to open said contacts.

4 aoeeeex 6. In combination, a. relay for controlling the charging of o. battery and having contacts which are opened and closed according to the movement of the relay armature, a, battery, o voltage source,

means responsive to source voltage for moving 5 said armature in the direction to close said conteats, means responsive to battery voltage and independent of sourcevoltoge for moving said ormoture in the direction to open seioi contacts, means responsive to current flowing irom sole] source to said bet through said contacts for maintaining said contacts 010, and permanent "owitchless circuit connections between said foot- 

